Abstract: Model reduction for the conversion of a higher order transfer function to one of lower order and for the online search of optimal controller parameters in a control system are band on a direct search procdure using pseudo random numbers. The paper abc at retaiining all the advachges of the optimization procedure and presents an improved method on the changeable range of the region of search i.e. in order to reach rapidly the optimum the change of reduction factor h is bed on the she of the objective function. Simulation results show that the optimum can be reached when using the improved method in only 10- 15 iterations when compared with the LJ method,and computer (CPU) the can be reduced by 20%-50%.